JPH0340291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric instantaneous water heater.

Conventional configuration and its problems In the conventional electric instantaneous water heater shown in FIGS. 1 and 2, for example, a sheathed heater 1, a water inlet pipe 2, and a hot water outlet pipe 3 are brazed to a heat exchanger 4 in a watertight manner. A flow rate operation switch 5 is watertightly connected in the middle of the water inlet pipe 2,
The heat exchanger 4 is fixed to the chassis 8 by bolts 16, nuts 6, and spring washers 7.
Moreover, since it is used in a humid place such as a bathroom, power is distributed via an earth leakage breaker 14 or the like. Kotoku 1
2 is opened to allow water to flow through, the flow rate switch 5 is linked to energize the sheathed heater 1, and the water flowing in through the water inlet 9 is heated and flows out through the outlet 10. Considering the environment in which an electric instantaneous water heater is used, it can be used in a humid place such as a bathroom or shower room, and in a state where the human body is completely naked and wet, as shown in Figure 2. Touch the metal part of Nakotoku 12. If the electrical insulation of the sheathed heater 1 deteriorates, a large current will flow through the heat exchanger 4, external piping 13, and pot 12 to the human body, resulting in a very dangerous situation. To prevent this, earth 15
However, even in this case, the human resistance can be determined from Figure 5 (upper limit of a-line, dry average value of b-line, lower limit of humidity of c-line).
Rm=1.3KΩ (lower humidity limit, contact voltage 220V), earth 1
5 is the grounding resistance Re assuming that type 3 grounding work has been performed.
= 0.1KΩ, in the equivalent circuit of the leakage current of the conventional product shown in Figure 6, the current Im flowing through the human body when the electrical insulation resistance Ri of the sheathed heater 1 is changed from ∞ to 0 is as shown in the graph of Figure 8. This is the same as line a.
In the worst case, when Ri=0, Im=162mA, which is fatal to the human body. That is, grounding 15 alone cannot be said to be safe depending on the conditions. Therefore, in the past, an earth leakage breaker 14 was sometimes installed for further safety, but in this case, the insulation of the sheathed heater 1 actually deteriorated only slightly, with little effect, and the earth leakage breaker 14 was installed. However, the electric instantaneous water heater main body 11 is no longer energized and cannot be used. Furthermore, as shown in Fig. 4, in hot water storage type electric water heaters, the method of electrically insulating the body 21 of the hot water storage type electric water heater with an external insulating tube 22 with a length of about 1 m was conventionally used. When used in water heaters, the piping work was complicated, and the outside of the main body was not electrically insulated. In addition, since the sheathed heater 1 and heat exchanger 4 in the high temperature section are thermally connected to the flow rate switch 5, etc., the temperature of the flow rate switch 5 rises when the heater is abnormally heated, resulting in drawbacks such as failure or malfunction. .

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks.
The purpose is to suppress leakage current as much as possible even when the electrical insulation of the heater deteriorates, thereby enabling safe and normal use.
The purpose is to prevent other parts from heating.

Structure of the Invention In order to achieve the above object, the present invention comprises a main body exterior including a front case and a back chassis,
The interior thereof includes a heat exchanger, a water supply pipe and a hot water outlet pipe that are watertightly connected to the heat exchanger, and the water supply pipe and hot water outlet pipe are partially or entirely made of electrically insulating material. , the chassis is raised in the shape of a bowl at the center and has a fixing hole at its apex; the heat exchanger is provided with a protrusion lower than the raised height of the central part of the chassis in the center of the back surface, and the protrusion is electrically connected. The heat exchanger is electrically insulated by an electric instantaneous water heater that is fixed to the fixing hole via a two-stage stepped spacer made of an insulating material and a washer and nut also made of an electrically insulating material. It is something.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, a sheathed heater 1, a water supply pipe 2, and a hot water outlet pipe 3 are watertightly connected to a heat exchanger 4 via an insulating pipe 17, and a flow rate operation switch 5 is watertightly connected in the middle of the water supply pipe 2. Bolt 1 for heat exchanger 4
6 is soldered. This bolt 16 is attached to the fixing hole 8 in the bowl-shaped raised portion 8b of the chassis 8.
A, a metal nut 6, a flat washer 20, and a spring washer 7 are fixed to each other via a stepped spacer 18 made of an electrically insulating material and a washer 19 also made of an electrically insulating material. The method of heating the running water is no different from the conventional example, so a description thereof will be omitted. When the electrical insulation of the sheathed heater 1 has deteriorated, the electricity leaking from the sheathed heater 1 is
When a human body touches the heat exchanger 4, the water inside the insulated pipe 17 flows to the human body via the water supply pipe 2, the hot water outlet pipe 3, the external pipe 13, and the pot 12.

FIG. 7 shows an equivalent circuit at this time. human body resistance
Rm = 1.3KΩ, earth grounding resistance Re = 0.1KΩ, electrical resistance of water inside insulation tube 17 Rw = 20KΩ (insulation tube 17
Inner diameter 8mm, insulation length 30mm, water conductivity 300μ
), the electrical insulation resistance Ri of sheathed heater 1
Current flowing through the human body when changing from ∞ to 0
Im is as indicated by line b in the graph of FIG. In the worst case, Ri = 0, Im = 1.6 mA, which is sufficiently safe for the human body. Also, from Figure 8, sheathed heater 1
Even if the electrical insulation in No. 5 deteriorates to 6KΩ, the human body can still use this electric water heater without feeling any electricity (Im = 1mA when Ri = 6KΩ). Furthermore, this insulation tube 1
5 is compact and has a main body 11 as shown in FIG.
Since the main body 11 itself has a two-stage insulation function, the external piping 13 in FIG.
There is no longer a need for electrical insulators such as PVC.
Metal parts on the main body surface that are likely to be touched by the human body, such as the bolts 16 for fixing the cover, are also insulated in two stages. In addition, since the sheathed heater 1 and heat exchanger 4 in the high temperature section are not thermally connected to the flow rate switch 5, chassis 8, etc., even when the heater is abnormally heated, the temperature of the flow rate switch 5, etc. is low, eliminating failures and malfunctions, and preventing the chassis from malfunctioning. 8, the temperature rise on the mounting walls, etc. also became lower.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) The heat exchanger is fixed to the chassis at one central location by stepped spacers and washers made of electrically insulating material, while the water supply pipes and hot water outlet pipes are electrically fixed by insulating pipes made of electrically insulating material as well. Since it is insulated and thermally insulated, it can be used safely and normally even when the sheathed heater insulation deteriorates, and other safety devices such as an earth leakage breaker are not required. Furthermore, even when the heater is abnormally overheated, the temperature of functional parts such as the flow rate switch and the chassis can be kept low, eliminating failures and malfunctions, and the temperature of the mounting wall can also be kept low, improving safety.

(2) Since the insulating tube is inside the main body, there is no need for external piping with electrically insulating material.

This has the effect of

[Brief explanation of the drawing]

Figures 1a and b are front sectional views and side sectional views of a conventional electric instantaneous water heater, Figure 2 is a perspective view of an installation example of the electric instantaneous water heater, and Figures 3a and b are A front sectional view and a side sectional view of an electric instantaneous water heater which is an embodiment of the present invention, FIG. 4 is a front view of an installation of a storage type electric water heater showing another conventional example, and FIG. A graph of the relationship between contact voltages, Figure 6 is an equivalent circuit diagram of a conventional electric instantaneous water heater and a human body, and Figure 7 is an equivalent circuit diagram of an electric instantaneous water heater according to an embodiment of the present invention and a human body. 8 are graphs showing changes in the current passing through the human body as the heater insulation resistance deteriorates in the equivalent circuits shown in FIGS. 6 and 7. 2... Water supply pipe, 3... Hot water outlet pipe, 4... Heat exchanger, 6... Nut, 8... Chassis, 8a... Fixing hole, 8b... Raised ivy part, 11... Case, 16 ...Protrusion (bolt), 17...Insulation tube,
18...Stepped spacer, 19...Washer.

Claims (1)

[Claims] 1 The outer shell of the main body is composed of the front case and the back chassis, and the inside thereof is equipped with a heat exchanger, a water supply pipe and a hot water outlet pipe that are watertightly connected to the heat exchanger, and the water supply pipe and the hot water outlet pipe are connected to the heat exchanger. The tubes are partially or entirely made of an electrically insulating material, the chassis has a bowl-shaped central portion and a fixing hole at its apex, and the heat exchanger has a fixing hole at the center of the back surface. A protrusion lower than the raised height of the central part of the chassis is provided, and the protrusion is fixed to the fixing hole via a washer and nut made of an electrically insulating material as well as a stepped spacer with two outer diameters made of an electrically insulating material. An electric instant water heater.